Update git submodules

* Update docs/submodules/nfvbench from branch 'master'
  - Move container to tag 1.2.1

    Change-Id: I873c852f47d5ba2e3098908919f2b66dce02a1e8
    Signed-off-by: ahothan <ahothan@cisco.com>

diff --git a/docs/submodules/nfvbench b/docs/submodules/nfvbench
index 8d3c8d2..dd23f01 160000 (submodule)
--- a/docs/submodules/nfvbench
+++ b/docs/submodules/nfvbench
@@ -1 +1 @@
-Subproject commit 8d3c8d2eabdad243692a3a13c6e4099f149d5385
+Subproject commit dd23f012cd6f9efd89f091a096982562e3c6216d